Mobile devices such as smartphones and tablet computers are being put to an increasing variety of uses. Smartphones are generally used for mobile wireless communication applications, such as placing and receiving voice calls, sending and receiving mobile messages (e.g. text and/or multimedia), and accessing email, the Internet and other services relying on data communications. Some small-sized tablet computers are now being configured for communication through mobile wireless networks, and for messaging and data services similar to those of smartphones.
In addition to communicating through mobile wireless communication networks, the devices are configured for short-range wireless communications using Bluetooth and/or near-field communication (NFC). In particular, mobile payment systems are being rolled out in which mobile device users can pay for purchases using smartphones or tablet computers. The mobile payment systems typically rely on NFC communication between a mobile device and a payment terminal. However, NFC communications are susceptible to eavesdropping. An eavesdropping device located within communication range of an NFC transmitter can listen to and record NFC-based communications, and could potentially use the recorded information to perform fraudulent payments. The eavesdropping device can be located out of sight of the NFC transmitter, such as in a hidden location, and nonetheless listen to and record NFC communications.
Quick-response (QR) codes are two-dimensional bar codes that can encode information. QR codes are commonly located on printed advertisements, and enable users to access additional information relating to an advertised product. QR codes are typically static: they encode a particular piece of information, and do not change over time. QR codes can be read by mobile devices having a QR-reader application and a camera. A user can thus access additional content relating to an advertisement by scanning the QR code with the mobile device's camera. The QR-reader application running on the mobile device decodes the QR code scanned by the camera, and extracts a universal resource locator (URL) or other web-address encoded within the QR code, and retrieves the additional information using the URL.
The reading of a QR code requires a direct line-of-sight between the QR code and the QR reader/camera, to enable the reader/camera to obtain an image of the code. As such, a user can limit access to a QR code by monitoring lines-of-sight to the QR code. In at least this respect, QR codes cannot readily be eavesdropped upon by devices not visible to the user. A QR code can thus be kept secure by limiting the period of time it is displayed or exposed, and/or monitoring the line-of-sight to the QR code.